These are the changes in Apple Raid 1.1:
RAID Driver
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Reinitializing the drives is no longer necessary when implementing RAID. The Administrator must install the Apple RAID disk driver on each hard disk that will contain mirrored or striped volumes. The easiest way to install the Apple RAID disk driver is to use the Install Driver command. The Install Driver command is also recommended for older versions of Apple RAID drives.
Apple RAID will now be "installable" over the Apple hard disk driver. Previously, a user needed to "reformat" a disk drive to use Apple RAID.
The Get Info command displays the amount of free space within a volume, and the Apple RAID Setup program displays the amount of disk space not allocated to a volume.
Weighted Striping
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Apple RAID allows up to eight partitions per disk; stripe and mirror partitions can reside on the same disk. Apple RAID volumes are limited to 2 GB with no more than 10 Apple RAID volumes per server system. If the server has more than one SCSI bus, the partitions should reside across both buses. A striped volume is limited to a maximum of 4 GB or a minimum of 10 MB.
The main advantage of weighted striping is the ability to balance the data throughput of RAID volumes on two separate SCSI buses of unequal speed. For instance, the 8550/132 has both a 5 MB/s and 10 MB/s bus. Two drives are installed, one connects to the 5 MB/s channel, the other to the 10 MB/s channel. With normal striping, the maximum theoretical throughput on each SCSI channel is the speed of the slower bus. With "weighted striping" the RAID software optimizes throughput on both buses, taking into consideration that one bus is faster and "weighting" these transfers. The result should be better data throughput on the 8550/132 SCSI subsystem. The cabling, bracket and software, will be included as standard elements with all 8550 systems. The user will just need to add the second drive.
Server Manager Support
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Server Manager will receive error messages from Apple RAID, enabling system administrators to receive remote notification of a failed Apple RAID volume through e-mail, paging, or other Server Manager features.
Upgrades/Compatibility
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Apple RAID 1.1 is only supported on PCI-based workgroup servers. Since Apple RAID 1.1 is not supported on NuBus workgroup servers, no upgrades to version 1.1 are available.
Clarification
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The PCI RAID Card is not part of Apple RAID 1.1. The PCI RAID Card is an option for the Network Server 500 or 700, and requires the AIX operating system. The PCI RAID Card is not Mac OS compatible.
Article Change History:
09 May 1996 - Added clarification section.